Two-way valveless pump



June 26, 1962 D. s. CUSHING TWO-WAY VALVELESS PUMP 2 Sheets-Sheet 1 Filed Dec. 30, 1959 FIGI INVENTOR.

DONALD s. cusume H )5 ATTORNEY June 26, 1962 D. s. CUSHING 3,040,663

TWO-WAY VALVELESS PUMP Filed Dec. 30, 1959 2 Sheets-Sheet 2 JNVENTOR. DONALD S. CUSHING HIS ATTORNEY United States Patent 3,040,663 TWO-'WAY VALVELESS PUMP Donald S. Cushing, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Dec. 30, 1959, Ser. No. 863,016 9 Claims. (Cl. 103,-2)

The present invention relates to the two-way pumping action of a reversible pump where there are no valves for opening and closing the discharge ports. This invention is directed toward pump structure per se but it is particularly advantageous as the drain pump of an automatic dishwasher. 1

Two-way pumps have been known in the art for many years but as a general rule they have all included a valve arrangement for alternately'opening and closing the two discharge ports so that only one port will be open at a time. These pumps work satisfactorily when new but the more moving parts that are included in a design the more chance for wear to take place and for failure to occur. An optimum design for a pump would be one having the least number of moving parts. 7

.The principal object of the present invention is to provide a two-way valveless pump with two discharge ports that are alternatively opened and closed in opposition to each other depending upon the direction of rotation of the pump impeller.

A further object of the present invention is to provide 7 a two-way valveless pump where the discharge ports are combined with a sump that serves to direct the flow of water through one port while stopping any flow through the other port.

The present invention has several modifications but the preferred embodiment comprises a pump housing having a bottom wall, a circular sidewall and a top wall having a central opening formed therein that cooperate to define a pump chamber with an inlet. A multi-bladed impeller is rotatably mounted about a central axis of the chamber and it is capable of being driven in either a clockwise or a counterclockwise direction. The side wall of the housing includes a pair of closely spaced discharge ports that are arranged adjacent the periphery of the impeller so -asto extend out from the chamber generally transverse to the flow of liquid caused by the impeller. The bottom wall of the housing is recessed in the vicinity of the two discharge ports so that the ports are respectively positioned within the recess at opposite circumferential ends of the recess. In eifect, the recess forms a sump which constitutes a minor part of the wall within which the recess is formed. The junction of the sump and the remainder of the chamber forms arcuately shaped side walls or dams that are joined with the outermost sides of the two discharge ports for directing the flow of water into the ports. As is the case with the ports, both dams are disposed generally transverse to the flow of liquid caused by the impeller. Each dam is associated with a port, and is positioned on the side of its associated port which is circumferentially remote from the other of the ports. The rotation of the impeller in one direction will force. the water to flow over one dam and into the sump where it will strike the other dam and be directed toward the related discharge port. The flowing of the water over the first mentioned dam will create a low pressure area at the first discharge port thereby preventing flow through that port. The reverse action is obtained when the impeller is turned in the opposite direction.

My invention will be better understood from the fo lowing description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

Ice

' way pump embodying thepresent invention suspended below the bottom wall of the tub of an automatic dishwasher with the drive motor positioned below the pump. 7 FIG. 2 is a cross-sectional plan view of the pump of FIG. 1 taken along the line 22 of FIG. 1.

FIG. 3 is a fragmentary elevational view looking from the inside of the pump chamber toward the two discharge ports and taken on the line 33 of FIG. 2.

FIG. 4 is a second modification of the present invention partly in cross-section showing in plan view the two discharge ports vertically disposed in the bottom wall of the pump housing.

FIG. 5 is a fragmentary elevational view taken on the line 5-5 of FIG. 4.

FIG. 6 is'a third modification of the invention showing in plan view the two discharge ports in the side wall of the pump housing, one above and one below the impeller.

FIG. 7 is a cross-sectional elevational view of the third modification taken on the curved line 77 of FIG. 6.

' Turning now to a consideration of the drawings and in particular to FIG. 1, there is shown a pump 10 embodying the present invention suspended from a collar 11 that is fastened to the underside of a tub 12 of an automatic dishwasher. While this invention is illustrated as being incorporatedin an automatic dishwasher it should be appreciated that the invention has general utility in the pump art; and the use to which the invention is to be put is not to be considered as a limitation of the invention. The bottom. wall of the tub 12 is generally conical or funnel shaped to form a sump 13 in which is positioned a wash impeller 14 for paddling the water in the sump upwardly through the dish racks (not shown) in the tub and scouring the soil from the load of dishes. The wash impeller 14-is fastened on the vertical shaft 15 of a drive motor 16 of the dishwasher. The bottom wall of the tub 12 is provided with a drain opening 17 for emptying'the water in the sump axially into the pump 10. The edge of this drain opening 17 is rolled under as at 18 for gripping the collar 11 that is adapted to support the pump housing from the bottom of the tub. A clamping member 19 is used to join the top portion of the pump with the collar 11 as is best shown in FIGURE 1. p

The motor 16 is suspended. from the pump housing by means .of fastening bolts 20 ina conventional manner which will not be described herein detail as it forms no part of the present invention. The shaft 15 of the motor FIG. 1 is a cross-seotional elevational view of a twoextends through the bottom of the pump housing and upwardly through the drain opening 17 in. the tub. This shaft supports both the wash impeller 14 and a pump im-. peller 21 so that operation of the motor turns both im-. pellers. The wash impeller14 is a double-bladed impeller while the pump impeller 21 is a multi-bladed impeller having forexample. fi-ve blades. Each blade of the pump impeller 21 has a substantially horizontal supporting POI. tion 22 extending from a hub 23 of the impeller, and a down-turned paddle portion 24. 7

Reference will now be made in FIGURES 2 and 3 of the drawing for an understanding of the preferred embodiment of the pump housing. The pump has been illustrated as being made of molded insulating material such as hard rubber, but in actual practice there is a metal insert over which the rubber is molded to form a reinforced rubber housing. Hence there will be no metaltometal contact between the motor and the housing and the housing and the tub. The pump housing 10 is generally. cylindrical in shape having a bottom wall 25, cir+ cular side walls 26 and an open top portion. The central axis of the cylindrical housing coincides with the rota- .tional axis of the motor shaft 15.

In this particular dishwasher it is important that the pump be a two-way pump because the pump serves a dual .function of either draining the tub or supplying water 7 to a rotating spray nozzle (not shown) on the underside of the cover of the tub for rinsing the soil from the dishes on the top rack. These two functions do not ocdirections. In the reverse direction of rotation when the tub is tobe drained, the wash impeller will draw the water toward the sump and out through thedrain opening 17 axially into the pump impeller 21.

Looking at FIGURES 2 I d 3 the side walls 26 of the pump housing include a pairv of discharge ports 27 and 28 which are closely spaced from each other and are each provided with a nipple over which flexible hoses (not shown) may be installed for carrying off the water that is pumped through the respective ports. Adjacent the inner ends of the discharge ports 27 and 28 is a sump 30 which is formed as a recess in the floor of the bottom wall 25 of the pump housing. This recess or sump 30 is formed with arcuately shaped side walls or dams 31 and 32 which are joined to each other near the center of the bottom wall, and then curve outwardly and toward the outermost sides of the twodischarge ports 27 and 28 as is best-illustrated in FIGURE 2. Port 27 cooperates with dam. 31 while port 28 cooperates with dam 32. When the pump impeller 21 is turning in the clockwise direction as seen in the plan view of FIGURE 2, the water will spill over dam 32 and flow against the opposite dam 31 causing some of the water to be directed into the discharge port 27 that is connected with a spray nozzle (not shown) in the upper portion of the tub. Simultaneously, the other discharge port 28 will be closed due to a low pressure area at substantially zero pressure above atmospheric pressure that is created by the water spilling over the adjacent dam 32. Accordingly, when the motor shaft 15 is'turning in theclockwise direction the wash impeller 14 will propel some of the water in the sump 13 upwardly into the tub, while the pump impeller 21 will draw elf some of the water from the sump and discharge it through the port 27 from which it is carried upwardly to- .the top of the tub for rinsing the dishes in the top rack In the reverse direction, when the motor shaft is turning in the counterclockwise direction the wash impeller 14 will draw the water down through the drain opening 17 and axially into the pump chamber. 'The drain impeller 21 will cause the water to spill overthe dam 31 and against the opposite vdam 32 thereby closing port 27 and directing the water through the larger discharge port 28 that carries the water ofi to a sewer connection. The top surface of the bottom wall 25 of the pump housing is gradually sloping from a high point 35 shown in FIGURE 1 that is diametrically opposite the two discharge ports 27 and 28 and slopes gradually downward on both sides of the motor shaft toward the sump 30. The drop in the sloping floor is measured between the high point 35 and a low point 36, where the sloping floor meets the dam 31. Notice in FIG. 3 that the tops of the dams are approximately at the mid-height of the two discharge ports 27-and 28. By varying the relationship between the diameters of the discharge ports, the dam height, and theposition of the top of the dam to the top of the discharge port, various pump rates can be'obtained. These variations do not materially affect the characteristics of the other discharge port as long as certain minimumphysical dimensions are held, depending upon the pump, size and the speed of rotation.

In this particular combination where the wash impeller is mounted on the same shaft as the pump impellerthere are different pump feeding characteristics in each direction of rotation of the wash impeller. For example, a vortex is formed by the Wash impeller as it turns in the counterclockwise direction to drain the Water of the tub into the pump. A pump inlet flow conditioner 37 of substantially conical shape is lowered into the pump through the drain opening 17. The lower portion of the flow conditioner 37 is provided with a circular opening 38 that is only slightly larger than the hub of the pump impeller 21. In addition the conical walls of the flow conditioner are provided with a small number of holes 39 for increasing the amount of water that is capable of flowing through the drain opening in the tub and axially into the pump impeller 21. This flow conditioner 37 directs the inlet flow axially into the central part of the pump impeller and it also prevents small objects such as nuts, bolts, or other hardware from entering the pump and damaging the mechanism.

. Turning now to a consideration ofthe second modification of FIGS. 4 and 5, the pump housing is identified as elementSll having a bottom wall 51, circular side walls 52 and an open top portion. A pump impeller 53 is positioned in the center of the pump housing for rotation in' either a clockwise or counterclockwise direction. In the preferred embodiment of FIGS. 1-3 the two discharge ports extend radially through the side walls from the center of the pump chamber. The second modification has the two discharge ports 54 and 55 extending vertically downward through the bottom wall 51 of the pump chamber. It is important that a sump and asso ciated dams be combined with the discharge ports for controlling the water. leaving the pump chamber. A sump 56 is provided in the side Walls 52 of the pump housing by locating the discharge ports 54 and 55 in the plane of the cylindrical side wall 52 and then extending the side walls around the two discharge ports so that the sump is actually vertically arranged in one section of the side wall. The dams are of arcuate shape and are formed by the sides of the sump namely at 57 and 58 as seen in FIG. 5. This modification will operate in a manner quite similar to that of the preferred embodiment of FIGURES 1-3. When the pump impeller 53 is turned in the clockwise direction the water will be discharged through the port and port 54 will be closed. When the pump impeller is turned in a counterclockwise direction the water will be discharged from port 54 and the opposite port will be closed.

The third modification of this invention is illustrated in FIGS. 6 and 7. This modification is similar to the preferred embodiment of FIGURES 1-3 in that the discharge ports 60 and 61 extend radially through the side walls of the pump housing 62. One distinction is that one port 60 is above the pump impeller 63 while the other discharge port 61 is below the impeller as is best seen in the elevational view of FIGURE 7. This modification alsohas a sump 64 that is formed by a pair of dams 65 and 66 to cooperate with the discharge ports and cause the water to build up atthe mouth of each port for passage therethrough. Dam 65'is formed by a dished cover or cap 67 which is fitted into the top of the pump housing 62 as is best seen in FIG. 7. The other dam 66 is formed as a recess in the bottom wall 68 of the pump housing.

Having described above my invention of a valveless two-way pump that is for use with a reversible motor, it should be appreciated by those skilled in this art that an important consideration in this invention is that the performance of each discharge port can be controlled to a large extent independently of the other port by variations in each dam'approach angle, dam height, discharge hole size and relative position of the dam to the dis charge port. Also variations may be made in the pump impeller such as turning the blades of the pump impeller upwardly instead of downwardly to use the full impeller area for carrying the water, thereby positioning the discharge ports above the impeller for most efiicient operation.

Modifications of this invention will occur tothose skilled in this art and it is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications'which are within the true spirit and scope of this invention as claimed.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A two-way valveless centrifugal type pump comprising a cylindrical housing with a bottom wall, a circular side wall, and a top wall having a central opening formed therein to define a pump chamber with an inlet, a multi-bladed impeller rotatably mounted about a central axis of said chamber, first and second circumferentially spaced constantly open valveless discharge ports arranged in said housing immediately adjacent the periphery of said impeller, each of said ports being formed to extend generally transverse to the flow of liquid caused by said impeller, a sump formed within said chamber as a recess extending into at least one of said walls thereof and arranged so that said ports are respectively positioned within said sump at opposite circumferential ends thereof, said recess constituting a minor part of the wall within which it is formed, the walls of said sump defining in part first and second upright dams each disposed generally transverse to the flow of liquid caused by said impeller, said first and second dams being respectively positioned adjacent said first and second ports, each of said dams being positioned on the side of its associated port circumferentially remote from the other of said ports, said first dam for one direction of impeller rotation causing a negative pressure within said sump adjacent said first dam so that said first port is also in a location of negative pressure, said second dam for said one direction of impeller rotation diverting the water out through said second port, the effects of said first and second dams on the liquid flow being reversed in the opposite direction of rotation of said impeller.

2. The apparatus defined in claim 1 wherein said two discharge ports are arranged adjacent and parallel to each other.

3. The apparatus defined in claim 2 wherein said two discharge ports extend outwardly through said side Wall and said recess is formed in said bottom wall.

4. The apparatus defined in claim 3v wherein said sump is recessed into said bottom wall of said housing and is formed by substantially curved upright side walls extending down' from said bottom wall.

5. The apparatus defined in claim 4 wherein part of each port is within said sump and the remainder of each port is above said sump thereby to create almost zero pressure at said first and second ports for said first and opposite directions of impeller rotation respectively.

6. The apparatus defined in claim 1 wherein said inlet to said pump includes a foraminous comically-shaped inlet flow conditioner extending downwardly toward said impeller.

7. The apparatus defined in claim 4 wherein said bottom wall slopes downwardly from a high point opposite said sump in both directions around the center of impeller to said sump.

8. The apparatus defined in claim 1 wherein said ports extend through said bottom wall of said pump housing and the portion of said side wall circumferentially including said ports is recessed to form said sump, the top wall of said sump being substantially semi-circular to provide arcuately shaped dams associated with each of said ports.

9. The apparatus defined in claim 1 wherein said discharge ports are located in said side wall of said housing, said first port being positioned above said impeller and said second port being positioned below said impeller, said sump being formed by a recess in said top wall forming said first dam and a recess in said bottom wall forming said second dam.

References Cited in the file of this patent UNITED STATES PATENTSv 772,989 Williams Oct. 25, 1904 2,258,284 Findley Oct. 7, 1941 2,838,002 Cohen June 10, 1958 2,864,312 Shelton Dec. 16, 1958 2,916,997 Terrie Dec. 15, 1959 2,946,286 Sholtes July 26, 1960 FOREIGN PATENTS 1,142,593 France Apr. 1, 1957 1,177,354 France Dec. 1, 1958 

